The HRT leak detector system consists of four headers each of which are connected on one side to a common supply of pressurized water and on the other side by individual tubing to the ring grooves of approximately twenty flanges. There are two methods of detecting the loss of water that are particularly applicable to the HRT: (1) By the loss of pressure in a constant volume system; (2) By the measurement of flow from a constant pressure system. It was determined to investigate the second method which requires a flowmeter capable of measuring flows of .5 cc or less of water per hour. The experiment flowmeter constructed performed almost exactly as the design calculations predicted.